This invention relates to automatic pipe cutting apparatus, and more particularly to such apparatus which makes a mitred cut and forms a constant angle bevel on the mitred cut.
To automatically weld two pieces of pipe together requires that the bevel of the joint be uniform. When the pipe is cut at 90.degree. to its longitudinal axis, the production of bevels of a constant angle is relatively simple; however, when the pipe is cut at an angle to form a mitred joint, for example 45.degree., if the bevel is to be uniform to produce a uniform groove for welding, the angle at which the bevel is cut must vary as the mitred cut follows an elliptical path over the surface of the pipe.
To produce high quality welds, the finish of the bevel is critical and must be of high quality to reduce costly rework. Inconsistency in the bevel can cause defects in subsequently made welds.
Commercial grades of pipe have certain discrepancies including circumferential out-of-roundness or lack of concentricity or differing wall thicknesses, which must be compensated for, if high quality welds are to be produced.